variety of sources, integrate and interpret that data, and select appropriate motor commands to achieve a movement goal. 5 Unfortunately, lateral ankle sprains and CAI result in feedback and feedforward neuromuscular control alterations. 6 Of particular interest are the altered muscle activity levels
Hooman Minoonejad, Mohammad Karimizadeh Ardakani, Reza Rajabi, Erik A. Wikstrom and Ali Sharifnezhad
Brent I. Smith, Denice Curtis and Carrie L. Docherty
This response can be attributed to the disordered function of proprioceptive and neuromuscular control components associated with the initial injury. 19 As a result, there is a greater dependence on proximal corrections and a subsequent reliance on a hip strategy to maintain balance. 18 , 20 This
C. Buz Swanik, Scott M. Lephart, Frank P. Giannantonio and Freddie H. Fu
Anterior cruciate ligament (ACL) injury disrupts static and dynamic knee restraints, compromising functional stability. Deafferentation of ACL mechan-oreceptors alters the spinal reflex pathways to motor nerves and muscle spindles in addition to the cortical pathways for conscious and unconscious appreciation of proprioception and kinesthesia. These pathways are required by the feed-forward and feedback neuromuscular control systems to dynamically stabilize joints. Feed-forward motor control is responsible for preparatory muscle activity, while feedback motor control regulates reactive muscle activity. The level of muscle activation, preparatory or reactive, influences muscular stiffness, thereby providing dynamic restraint for the ACL-deficient athlete. Rehabilitation protocols should incorporate activities that enhance muscle stiffness while encouraging adaptations to peripheral afferents, spinal reflexes, and cortical motor patterns. Four elements crucial for reestablishing neuromuscular control and functional stability are proprioceptive and kinesthetic awareness, dynamic stability, preparatory and reactive muscle characteristics, and conscious and unconscious functional motor patterns.
Sangeetha Madhavan, Sarah Burkart, Gail Baggett, Katie Nelson, Trina Teckenburg, Mike Zwanziger and Richard K. Shields
Neuromuscular control strategies might change with age and predispose the elderly to knee-joint injury. The purposes of this study were to determine whether long latency responses (LLRs), muscle-activation patterns, and movement accuracy differ between the young and elderly during a novel single-limb-squat (SLS) task. Ten young and 10 elderly participants performed a series of resistive SLSs (~0–30°) while matching a computer-generated sinusoidal target. The SLS device provided a 16% body-weight resistance to knee movement. Both young and elderly showed significant overshoot error when the knee was perturbed (p < .05). Accuracy of the tracking task was similar between the young and elderly (p = .34), but the elderly required more muscle activity than the younger participants (p < .05). The elderly group had larger LLRs than the younger group (p < .05). These results support the hypothesis that neuromuscular control of the knee changes with age and might contribute to injury.
Katrine Moreale, Jay Smith, David A. Krause and Diane L. Dahm
To examine the accuracy and reliability of upper limb target pointing among normal subjects.
Community sports-medicine practice.
28 male and female normal right-handed volunteers age 22–35 years.
8-point target-pointing task completed with both upper limbs.
Main Outcome Measures:
Accuracy of point reproduction (cm error) and reliability over time (ICC2,1).
Target-pointing errors were 4.8–9.9 cm. Subject error and reach height explained 88% of performance variability. Error was greater when pointing to the lower half of the target (P < .05) and to ipsilateral points (P < .05). Gender, test day, reach length, and arm dominance did not affect accuracy. Test–retest reliability ranged from .30 to .71.
Target-pointing tasks might be useful to assess upper limb neuromuscular control. Points with lower errors and greater reliabilities might be useful to differentiate normal vs abnormal performances, whereas a battery of reliable points over a spectrum of errors might be useful to document changes over time.
Mary E. Ubinger, William E. Prentice and Kevin M. Guskiewicz
When the upper extremity is injured, open kinetic chain (OKC) exercises are primarily used to increase strength and restore functional ability—the goals of rehabilitation. It is also imperative, however, that the receptors responsible for static and dynamic stabilization of the joint be trained. This can be done with closed kinetic chain (CKC) exercises. The purposes of this study were to investigate the effect of a 4-week CKC training program on the neuromuscular control of the upper extremity and to determine whether there was a significant difference between skill-dominant limb and nondominant limb stability indices. Thirty-two physically active participants (14 men, 18 women) were tested on the FASTEX 4 weeks apart. The training group's scores significantly improved, whereas the control group's scores remained the same. It was concluded that the CKC training significantly improved the training group's ability to remain stable. The results suggest that CKC training can increase the accuracy of joint position sense because of increased stimulation of the mechanoreceptors.
Kazem Malmir, Gholam Reza Olyaei, Saeed Talebian and Ali Ashraf Jamshidi
Cyclic movements and muscle fatigue may result in musculoskeletal injuries by inducing changes in neuromuscular control. Ankle frontal-plane neuromuscular control has rarely been studied in spite of its importance.
To compare the effects of peroneal muscle fatigue and a cyclic passive-inversion (CPI) protocol on ankle neuromuscular control during a lateral hop.
Quasi-experimental, repeated measures.
22 recreationally active, healthy men with no history of ankle sprain or giving way.
Participants performed a lateral hop before and after 2 interventions on a Biodex dynamometer. They were randomly assigned to intervention order and interventions were 1 wk apart. A passive intervention included 40 CPIs at 5°/s through 80% of maximum range of motion, and a fatigue intervention involved an isometric eversion at 40% of the maximal voluntary isometric contraction until the torque decreased to 50% of its initial value.
Main Outcome Measures:
Median frequency of the peroneus longus during the fatigue protocol, energy absorption by the viscoelastic tissues during the CPI protocol, and feedforward onset and reaction time of the peroneus longus during landing.
A significant fall in median frequency (P < .05) and a significant decrease in energy absorption (P < .05) confirmed fatigue and a change in viscoelastic behavior, respectively. There was a significant main effect of condition on feedforward onset and reaction time (P < .05). No significant main effect of intervention or intervention × condition interaction was noted (P > .05). There was a significant difference between pre- and postintervention measures (P < .0125), but no significant difference was found between postintervention measures (P > .0125).
Both fatigue and the CPI may similarly impair ankle neuromuscular control. Thus, in prolonged sports competitions and exercises, the ankle may be injured due to either fatigue or changes in the biomechanical properties of the viscoelastic tissues.
Paul J. Read, Jon L. Oliver, Gregory D. Myer, Mark B.A. De Ste Croix and Rhodri S. Lloyd
literature to examine the magnitude of between-limb differences in commonly used tests that measure neuromuscular control. Elite male youth soccer players have shown isokinetic strength imbalances of the hamstrings and quadriceps combined with reduced dominant leg hip range of motion ( 8 , 17 ). Kinetic